Tools for chip-removing machining of metal workpieces are generally composed of a rotatable tool body and a plurality of replaceable cutting inserts made of cemented carbide, ceramics, or other hard material. Since the cutting inserts are subjected to significant wear upon use in the tool, it is desirable for the insert to have as many edges as possible in order to prolong the service life of the cutting insert. Cutting inserts are therefore often made double-sided with cutting edges formed along both an upper side and a lower side of the insert, thus doubling the number of cutting edges per insert.
Double-sided cutting inserts may however have complicated geometries that make them difficult to manufacture using simple pressing processes, in particular uniaxial pressing processes. Instead, more advanced multi-axial pressing processes may be needed, increasing the complexity and cost of producing the cutting inserts. In order to overcome this problem, manufacturing methods have been developed in which the cutting insert is pressed by a uniaxial pressing of separate upper and lower compacted powder parts, which thereafter are sintered together to form a double-sided cutting insert.
EP0365505 discloses a cutting insert manufactured from two compacted powder parts sintered together. Each of the compacted powder parts is provided with a set of engagement members for preventing relative motion of the parts before sintering the parts together.
WO2014081011 discloses a tool for chip-removing machining and a cutting insert for mounting in such a tool, wherein the cutting insert is made by sintering two compacted powder parts together. The cutting insert is double-sided and provided with a waist shaped side surface, so that it has a positive basic shape. Each of the compacted powder parts is provided with a set of engagement members for preventing relative motion of the parts.
Although the separate compacted powder parts disclosed in EP0365505 and WO2014081011 are provided with engagement members, cutting inserts that are manufactured from two compacted powder parts that are sintered together tend to have geometrical imperfections. Such imperfections arise from slight misalignments of the two parts forming the cutting insert, as well as from errors arising from sintering. The symmetry of the cutting insert is thereby affected and when mounted in an insert seat of a tool body, it is difficult to achieve a precise positioning of the cutting insert. One way of compensating for such imperfections is to grind the cutting insert after sintering, but this is a costly and time consuming procedure which increases the final cost of the cutting insert. Furthermore, grinding increases the amount of waste material produced during production and which is difficult to renew. It is therefore desirable to find solutions by means of which cutting inserts that are formed from two parts sintered together can be used in tools for chip-removing machining, without additional grinding, after sintering.